1. Department of Radiology, National Health Insurance Service Ilsan Hospital, Goyang, Korea.
2. Research and Analysis Team, National Health Insurance Service Ilsan Hospital, Goyang, Korea.
3. Clinic of Radiology and Nuclear Imaging, University Hospital Basel, Basel, Switzerland.
4. Department of Radiology and Biomedical Imaging, University of California, San Francisco, 513 Parnassus Ave, San Francisco, CA 94117.